Story by Rong-Gong Lin II
“Vaccination remains one of the most effective ways to prevent severe disease and death from COVID-19,” said Dr. Aimee Sisson, the health officer for Yolo County. Above, Pfizer’s updated COVID-19 vaccine. ((Pfizer via Associated Press))
A COVID wave is washing over California, with the state seeing continued increases in the number of newly confirmed cases and hospitalizations as some officials urged the public to take greater precautions.
The extent of the recent increases has prompted some county-level health officials to recommend that residents once again consider wearing masks in indoor public settings, at least until transmission has declined.
California currently has “high” coronavirus levels in sewage, according to the U.S. Centers for Disease Control and Prevention. And increases are being seen across the Golden State, from Los Angeles County to the San Francisco Bay Area to areas around the state capital.
The CDC estimates that coronavirus infections are either “growing” or “likely growing” in 30 states, including California. Twenty-one states have either “very high” or “high” viral levels in wastewater. Of all regions of the U.S., the West has the highest levels of coronavirus in wastewater, followed by the South.
“California is experiencing a summer COVID wave,” said Dr. Aimee Sisson, the health officer in Yolo County, just west of Sacramento.
The rate at which coronavirus lab tests are coming back positive also continues to climb. For the week that ended Aug. 23, 12.07% of tests across the state came back positive, up from a rate of 6.03% for the week that ended July 26.Related video: Study: COVID-19 cases increase during summer (WKRN Nashville)
Johns Hopkins researchers say human behavior plays a major role.
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Study: COVID-19 cases increase during summer
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Similar leaps in rates were seen in L.A. County, where the positive test rate was 13.44%, up from 8.11% four weeks earlier; in Orange County, it was 18.1%, up from 9.4%; and in San Francisco, it was 8.7%, up from 7.1%.
Dr. Elizabeth Hudson, the regional chief of infectious diseases at Kaiser Permanente Southern California, said she received many calls related to outpatient cases of COVID-19 while on call over the Labor Day weekend.
“We are definitely seeing an upswing in patients with COVID,” Hudson said. “Thankfully, inpatient cases are few and far between. Wastewater levels, however, are still rising in Los Angeles, so we have not reached the top of this current wave.”
Overall, this summer hasn’t seen COVID activity to the extent of a year ago, when the state experienced its worst summer wave since 2022.
“We will have to see what direction things go over the next one to two weeks to have a better idea” of where we end up, Hudson said. Students returning to school as well as from travel and socialization over the holiday weekend, could fuel further spread of the virus, she said.
Across California, the overall level of COVID hospital admissions remains “low,” but is increasing.
For the week that ended Aug. 23, there were 3.62 hospital admissions for COVID for every 100,000 residents; up from a comparable rate of 1.9 four weeks earlier. The most recent rate is also higher than during the peak seen during the winter, which maxed out at 2.61 admissions for every 100,000 residents.
Emergency department visits for COVID-like illness are also up in Los Angeles, Orange and Santa Clara counties. In L.A. County, 2.8% of emergency room visits were for illnesses such as fever plus a cough or sore throat, up from 2.2% four weeks earlier. In Orange County, 2.6% of ER visits were for COVID-like illness, up from 1.5%.
“The current percent of COVID-19 positivity is higher than at any point last winter,” according to Dr. Christopher Zimmerman of the Orange County Health Care Agency’s Communicable Disease Control Division and Dr. Regina Chinsio-Kwong, the county’s health officer.
As of Aug. 23, 1.9% of total hospitalizations in Orange County were due to COVID — higher than at any point seen during the winter, but less than half of last summer’s peak of 4%.
However, it’s unclear “how high or how severe this summer’s COVID wave may be,” Zimmerman and Chinsio-Kwong said, noting that this year’s rise began later than it did in 2024.
In Los Angeles County, COVID-19 hospitalizations are currently about as high as last winter’s peak, but remain lower than the peaks of the last two summers, according to the L.A. County Department of Public Health.
Sisson said that coronavirus levels are high in the wastewater of both Sacramento and West Sacramento, one of the most populous cities in Yolo County. Sisson recommended that everyone age 2 and up in West Sacramento “wear a mask when they are around others in indoor public spaces,” since coronavirus levels in sewage there are high.